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Article

Spatiotemporal Intermittency in Pulsatile Pipe Flow

Center of Applied Space Technology and Microgravity (ZARM), University of Bremen, Am Fallturm 2, 28359 Bremen, Germany
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Entropy 2021, 23(1), 46; https://doi.org/10.3390/e23010046
Received: 4 December 2020 / Revised: 24 December 2020 / Accepted: 24 December 2020 / Published: 30 December 2020
(This article belongs to the Special Issue Intermittency in Transitional Shear Flows)
Despite its importance in cardiovascular diseases and engineering applications, turbulence in pulsatile pipe flow remains little comprehended. Important advances have been made in the recent years in understanding the transition to turbulence in such flows, but the question remains of how turbulence behaves once triggered. In this paper, we explore the spatiotemporal intermittency of turbulence in pulsatile pipe flows at fixed Reynolds and Womersley numbers (Re=2400, Wo=8) and different pulsation amplitudes. Direct numerical simulations (DNS) were performed according to two strategies. First, we performed DNS starting from a statistically steady pipe flow. Second, we performed DNS starting from the laminar Sexl–Womersley flow and disturbed with the optimal helical perturbation according to a non-modal stability analysis. Our results show that the optimal perturbation is unable to sustain turbulence after the first pulsation period. Spatiotemporally intermittent turbulence only survives for multiple periods if puffs are triggered. We find that puffs in pulsatile pipe flow do not only take advantage of the self-sustaining lift-up mechanism, but also of the intermittent stability of the mean velocity profile. View Full-Text
Keywords: unsteady shear flow; turbulence intermittency; helical instability; puff dynamics unsteady shear flow; turbulence intermittency; helical instability; puff dynamics
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MDPI and ACS Style

Feldmann, D.; Morón, D.; Avila, M. Spatiotemporal Intermittency in Pulsatile Pipe Flow. Entropy 2021, 23, 46. https://doi.org/10.3390/e23010046

AMA Style

Feldmann D, Morón D, Avila M. Spatiotemporal Intermittency in Pulsatile Pipe Flow. Entropy. 2021; 23(1):46. https://doi.org/10.3390/e23010046

Chicago/Turabian Style

Feldmann, Daniel, Daniel Morón, and Marc Avila. 2021. "Spatiotemporal Intermittency in Pulsatile Pipe Flow" Entropy 23, no. 1: 46. https://doi.org/10.3390/e23010046

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